利用XMLHTTP下载文件，和以前的方法一样，先添加引用－COM－Microsoft Xml 3.0，然后在代码开始处写：
using MSXML2;
下面就是主要的代码：
private void Page_Load(object sender, System.EventArgs e)
{
string Url = "http://dotnet.aspx.cc/Images/logoSite.gif";
string StringFileName = Url.Substring(Url.LastIndexOf("/") + 1);
string StringFilePath = Request.PhysicalApplicationPath;
if(!StringFilePath.EndsWith("/")) StringFilePath += "/";
MSXML2.XMLHTTP _xmlhttp = new MSXML2.XMLHTTPClass();
_xmlhttp.open("GET",Url,false,null,null);
_xmlhttp.send("");
if( _xmlhttp.readyState == 4 )
{
if(System.IO.File.Exists(StringFilePath + StringFileName))
System.IO.File.Delete(StringFilePath + StringFileName);
System.IO.FileStream fs = new System.IO.FileStream(StringFilePath + StringFileName, System.IO.FileMode.CreateNew);
System.IO.BinaryWriter w = new System.IO.BinaryWriter(fs);
w.Write((byte[])_xmlhttp.responseBody);
w.Close();
fs.Close();
Response.Write ("文件已经得到。<br><a href='" + Request.ApplicationPath + StringFileName +"' target='_blank'>");
Response.Write ("查看" + StringFileName + "</a>");
}
else
Response.Write (_xmlhttp.statusText);
Response.End();
}
